The present invention relates to a flat cable connector and, more particularly, to an insulation-displacement connetor with terminals whose center-to-center spacing is different than the spacing of the conductors in the flat cable to be connected.
Flat cables and insulation-displacement connectors are in common usage in the electronics industry. Such cables come in the form of flat ribbons composed of parallel metal conductors covered in a flexible insulating material and spaced the same as the connector terminal spacing. These terminals often embody two-pronged forks, spaced so that if pressure is applied to the flat cable, each fork pierces the insulating material on both sides of its corresponding conductor as well as the conductor itself which is wedged between the two prongs, (or tines) of the forks, thus assuring the electrical and the mechanical quality of the connection.
This type of interconnection offers many advantages over those obtained by soldering or by wire wrapping, amongst which might be mentioned the reduction obtained in the volume and in the weight of the connection, the flexibility of application, the rapid action and easy handling which contribute to lowering overall costs.
However, in electronics applications the flat cable connections must be effected with very small sized components. The conductor diameter of flat cables in thus about 3/10 of a millimeter with conductor and terminal spacing of 1.27 mm, for example. The spacing dimensions must be kept within a tolerance strict enough to ensure problem-free and reliable interconnections. Hence, special types of connectors are designed for use with flat cables.
Long before flat cables became available, miniaturized connectors already existed, generally rectangular in shape, with a single or double row of terminals, and of a size very close to that of the new flat cable connectors. Proved in the field by usage and possessing certain highly desirable features, these older connectors are still widely used. Moreover, their terminal tails, which were originally designed for soldering or wire wrapping, can be re-designed for "insulation piercing" for use with flat cables. However, a problem is encountered due to the fact that the spacing between terminal center axes of these existing rectangular connectors does not correspond to the spacing of the conductors in flat cables. For example: the center-to-center spacing between contacts of the same row in this type of connector is 2.76 mm and 1.38 mm between alternate contacts in the case of a double row of terminals. Obviously, even in the most favorable arrangement of connecting two adjacent cable conductors to two ordinaly successive terminals along the long axis of the connector, i.e. one in each row, there would remain a gap of 0.1 mm (1.38 mm - 1.27 mm). Considering the cumulative error over the full range of the terminals and conductors, it is evident that the miniaturized rectangular connectors with insulation piercing terminals cannot be used directly for interconnecting the flat cable.
However, the desirability of being able to interconnect these connectors with those having a terminal spacing suitable for flat cables led to the development of special devices for this purpose. Some of these devices, either manually operated, or automatic, cut the insulation between the conductors in the flat cable, and "fan-out" the insulated conductors to match up with the spacing of the terminals in the connector.
Other means employed to the same end consist of providing intermediate, mechanical type adapters. These devices are costly, often complicated in nature, and in all cases contrary to the primary purpose of flat cable usage, which is the possibility of a rapid and single movement interconnection of the whole set of cable conductors.
The purpose of this invention is to eliminate the disadvantages cited, simply and economically, by a means which is limited solely to slanting the flat cable at an appropriate angle when presenting it to the insulation piercing terminals of the connector, and adopting a certain geometric arrangement of the insulation piercing terminals, and to providing a cable clamp, having a cover so designed as to correct the deviation from its normal axis which is imposed upon the flat cable by the connector, and to realign the segment of the cable issuing from the connector to the normal axis of the cable.